The goal of the University of Pittsburgh Obesity and Nutrition Research Center (ONRC) is to develop more effective interventions for the prevention and treatment of obesity. This focus is significant since there are 34 million Americans who are obese, and current efforts at treatment and prevention are only moderately successful. The University of Pittsburgh is uniquely qualified to focus on intervention research, since the Director and Associate Director, Drs. Rena R. Wing and Leonard H. Epstein, are internationally known for their research on this topic. Currently, there are more than 50 NIH-funded research projects at the University of Pittsburgh related to obesity and nutrition. These projects are being executed by researchers in the Departments of Psychiatry, Epidemiology, Medicine, Pediatrics, Obstetrics and Gynecology, and Psychology. An ONRC at the University of Pittsburgh would promote multidisciplinary research between these investigators and strengthen collaboration between those who focus primarily on intervention strategies and those who focus on the metabolic processes associated with obesity; an ONRC would also help generate comparative research across the lifespan, as there are obesity researchers in Pittsburgh studying the problem from infancy through old age. To facilitate collaborative research aimed at developing more effective interventions for the prevention and treatment of obesity, the Pittsburgh ONRC will establish Enrichment Programs, a Pilot/Feasibility Grant program, and four Core Facilities: An Administrative Core (with statistical consultation), a Clinical Assessment Core (to provide histories/physicals; phlebotomy procedures; measures of body composition and energy expenditure; psychological assessments; a database of obese patients and their family; and to facilitate recruitment of patients for obesity studies), a Laboratory Core (for assays of lipids, lipoproteins, glucose, insulin, amino acids, and reproductive hormones), and a Nutrition/Eating Behavior Core (with resources for analysis of eating records and a laboratory for direct observation of eating behavior). The focus of the Pittsburgh ONRC on intervention research should complement that of other centers and promote scientific research on the critical issues of treatment and prevention.